The chemical warfare involved in endophytic microorganisms-plant associations

Abstract Endophytes including bacteria and fungi have the ability to colonize internal plant tissues and live in association with their respective hosts without causing any disease symptoms. Interactions between the two partners depend on genetic dispositions, their developmental stage, nutritional status, and environmental factors. Endophytes, therefore, may represent an eco-friendly option to mitigate biotic and abiotic stresses in plants. Endophytes have been associated with the production of secondary metabolites that may confer environmental advantages to the host, increasing its adaptability and may benefit the host plants concerning better tolerance to biotic and abiotic stresses. However, the colonization of endophytes may overcome obstacles, and plants have developed several mechanisms to counteract the fungal attack, including the synthesis of defensive phytochemicals. Some endophytes appear to possess the ability to manipulate host plant metabolism, and during the coevolution with plants, microorganisms developed the strategy to inject effectors into plants in order to suppress the host resistance. In response, plants have developed receptors that recognize the pathogens effectors. The endophytic strategies used to colonize the plant, and the host responses will be approached here. Thus endophytes may be a rich and reliable biological source of active compounds with potential benefits in medicinal, industrial, and mainly agricultural applications. Therefore it is important to explore and understand such endophytic-host interactions to achieve a possible environmental sustainability in the future.